I doubt many Russians can tell the difference between Ukrainian and Polish either. I unironically think that some of them convinced themselves they were fighting Polish mercenaries just because they heard western Ukrainian accents.
Hearing Ukrainian for the first time, if you're Russian, sounds like you're hearing a Russian dialect you never heard before but understand 90% of, bar some words you've never heard. The languages are that close.
Polish, otoh, would baffle a Russian at first, you'd grasp quite a bit but you know you're hearing a foreign language, Slavic but foreign.
For example it shows EN/DE and EN/NO as having equivalent distances (49) when obviously EN/DE are much closer than either is to NO (in any holistic comparison of the three languages). It also shows IT/FR as being significantly closer (31) than IT/SP (40) when that's also plainly not the case -- again if we consider the distance between respective language pairs holistically (which includes a whole lot of other factors like phonemic footprint, meter, etc).
In short this reads like pretty much the kind of post one would expect from a "brain candy" site like this.
Less harshly (assuming good indent on the author's part), it demonstrates the pitfalls of relying on a single score (which in itself can be subject to all kinds of weighting and sampling biases) simply because it's a "score" and we're all supposed to be "data-driven" in our analyses these days.
But again -- nifty diagrams, and they do at least give a feel for the topic of mutual intelligibility and language distance (even if the scores themselves don't seem to be particularly meaningful).
From the other side, my Czech friends told me that Polish sounded to them like something from deep antiquity. Like reading an ancient manuscript where again you get the words but no sane person these days would use them like this.
My grandparents and parents and siblings all learned Ukrainian in school during Soviet times. This is in what now would be considered a predominantly Russian-speaking part of Ukraine btw.